Liquid injection molding apparatus

ABSTRACT

A liquid injection molding apparatus is provided. The liquid injection molding apparatus comprises a mold assembly; a clamping unit; an injector including a barrel; a feed screw concentrically located in the barrel; and a motor having a drive shaft removably coupled to the feed screw via a bayonet connector.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of prior U.S. application Ser.No. 15/481,171, filed Apr. 6, 2017, now U.S. Pat. No. 10,807,286, whichis incorporated by reference herein in its entirety.

FIELD

The invention relates generally to a liquid injection molding apparatusand, in particular, to a liquid injection molding apparatus having afeed screw that can be quickly coupled to and decoupled from a driveshaft.

BACKGROUND

Liquid injection molding injects a moldable liquid into a mold to form asolid article. The moldable liquid is a mixture such as thermosets orliquid silicone rubber (LSR) that is in the liquid state at roomtemperature and when heated cures into a solid. Some mixtures can alsocure at room temperature if left at room temperature over a period oftime.

The barrel of a liquid injection molding apparatus may require frequentcleaning. Reducing the time the liquid injection molding apparatus isoffline for cleaning is desirable.

BRIEF SUMMARY

In an illustrated embodiment, a liquid injection molding apparatus isprovided. The liquid injection molding apparatus comprises a moldassembly; a clamping unit; an injector including a barrel; a feed screwconcentrically located in the barrel; and a motor having a drive shaftremovably coupled to the feed screw via a bayonet connector.

The bayonet connector can include a receiver, and an insert including afirst end, and a second end distal from the first end. The first endremovably coupled to and housed in the receiver. The second end coupledto the feed screw. The drive shaft including a hollow portion having anon-round cross-section. The receiver shaped for a snug fit and housedin the hollow portion such that rotating the drive shaft about an axisof the drive shaft rotates the receiver.

The receiver can include an axial opening, and a wall including aninterior surface defining a cylindrical space connected to the axialopening. The wall including at least one lug projecting from theinterior surface into the cylindrical space, distal from the axialopening. The insert including an exterior surface and at least one sloton the exterior surface at the first end. The at least one slot havingan axial leg and a circumferential leg. The circumferential leg formingan acute angle with the axial leg at a junction. The axial leg includinga third end distal from the junction. The third end including an axialopening to permit the at least one lug to enter the at least one slotwhen the third end engages the at least one lug. The circumferential legincluding a fourth end distal from the junction such that rotating thereceiver about an axis of the receiver in an angular direction to seatthe at least one lug in the fourth end rotates the insert.

The receiver can include an axial opening, and a wall including aninterior surface defining a cylindrical space connected to the axialopening. The insert including an exterior surface having at least onelug, at the first end, projecting radially away from the exteriorsurface. The interior surface including at least one slot having anaxial leg and a circumferential leg. The circumferential leg forming anacute angle with the axial leg at a junction. The axial leg including athird end distal from the junction. The third end including an axialopening to permit the at least one lug to enter the at least one slotwhen the third end engages the at least one lug. The circumferential legincluding a fourth end distal from the junction such that rotating thereceiver about an axis of the receiver in an angular direction to seatthe at least one lug in the fourth end rotates the insert.

The liquid injection molding apparatus can further comprise a collet.The drive shaft including an axial opening connected to the hollowportion. The collet threadably connected to axial opening of the driveshaft to inhibit axial displacement of the receiver within the hollowportion thereby inhibiting the at least one lug from moving away fromthe fourth end.

The receiver can include another axial opening, distal from the axialopening of the receiver, connected to the cylindrical space. The firstend of the insert extends through the receiver passing through bothaxial openings of the receiver.

The at least one lug can include more than one lug and the at least oneslot can include more than one slot, each slot engaging a respective oneof the more than one lug.

The insert can be threadably connected to the feed screw.

The exterior surface of the insert can include two radially spaced apartplanar portions.

The wall of the receiver can include an exterior surface including fourplanar sides and four chamfers. Each chamfer connecting twointerconnected planar sides of the four planar sides. The at least onelug can include four lugs and the at least one slot can include fourslots. Each lug located at a respective chamfer.

The receiver can include an exterior surface including four planar sidesand four chamfers. Each chamfer connecting two interconnected planarsides of the four planar sides. The at least one lug include four lugsand the at least one slot can include four slots. Each axial leg of theslots located at a respective chamfer.

The at least one slot can extend from the interior surface of thereceiver completely to the exterior surface of receiver.

The hollow portion can have a rounded rectangular cross-section.

The hollow portion can have a hexagonal cross-section.

The hollow portion can have an octagonal cross-section.

The hollow portion can have a D-shaped cross-section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a liquid injection molding apparatusaccording to an embodiment of the present application;

FIG. 2 is a side view of an injector of FIG. 1 according to anembodiment of the present application;

FIG. 3 is a top view of the injector of FIG. 2;

FIG. 4 is a top partially cutaway view of the injector of FIG. 2 showinga magnified view of the bayonet connector removably coupling the feedscrew to the drive shaft of the feed screw motor, according to anembodiment of the present application;

FIG. 5 is an exploded perspective view of the bayonet connector of FIG.4 with its associated components;

FIG. 6 is a perspective view of the receiver of the bayonet connector ofFIG. 4;

FIG. 7 is a cross-section view of the receiver of FIG. 6 taken alongline A-A of FIG. 6;

FIG. 8 is a perspective view of the insert of the bayonet connector ofFIG. 4;

FIG. 9 is a side view of the insert of FIG. 8;

FIG. 10 is a perspective partial sectioned view of the feed screwcoupled to the drive shaft of the feed screw motor by the bayonetconnector of FIG. 4;

FIG. 11 is an exploded perspective view of the bayonet connector withits associated components in accordance to another embodiment of thepresent application;

FIG. 12 is an exploded perspective view of the bayonet connector of FIG.11 with the slots extending through the wall of the receiver from theinterior surface completely to the exterior surface; and

FIG. 13 is an exploded perspective view of the bayonet connector withits associated components in accordance to yet another embodiment of thepresent application.

DETAILED DESCRIPTION

Specific embodiments of the present application are now described withreference to the figures. The following detailed description is merelyexemplary in nature and is not intended to limit the concepts and usesof the concepts. Furthermore, there is no intention to be restricted byany expressed or implied theory in the present disclosure. In thedescription, “downstream” is used with reference to the direction of themoldable liquid flow from an injector to a mold cavity, and also withreference to the order of components, or features thereof, through whichthe mold material flows from the injector to the mold cavity, whereas“upstream” is used with reference to the opposite direction.

FIG. 1 is a schematic view of a liquid injection molding apparatus 10including an injector 15, a mold assembly 20, and a clamping unit 25. Inoperation, after clamping unit 25 clamps mold assembly 20 shut, injector15 injects a moldable liquid (not shown) into mold assembly 20. Afterthe moldable liquid cures into a solid article (not shown), clampingunit 25 opens mold assembly 20 to release the newly formed solidarticle. The process is subsequently repeated to create the next solidarticle.

FIG. 2 and FIG. 3 illustrate an embodiment of injector 15, whichincludes a linear actuator 30 and a feed screw motor 35, both coupled toa feed screw 37 (see FIG. 4 for a magnified view of feed screw 37removably coupled to feed screw motor 35), and concentrically located ina barrel 40, for reciprocating and rotating, respectively, feed screw 37within barrel 40. Injector 15 includes a nozzle 45 and an input valve50, nozzle 45 for controlling the moldable liquid dispensed frominjector 15 into mold assembly 20 and input valve 50 for receiving themoldable liquid from a source (not shown) into barrel 40. Linearactuator 30 includes a drive mechanism 55 and at least one motor 60.Drive mechanism 55 is coupled to motor 60 and feed screw 37 to convertthe rotational motion of motor 60 into a linear motion, which isimparted onto feed screw 37 to reciprocate feed screw 37 within barrel40. Linear actuator 30 moves feed screw 37 downstream to inject themoldable liquid into mold assembly 20 through nozzle 45 and retractsfeed screw 37 upstream to reload feed screw 37 with the moldable liquidfor the subsequent injection. (Depending on the application of injector15, one or two motor 60 may be used and feed screw motor 35 may be usedto rotate feed screw 37 to stir the moldable liquid within barrel 40.)

Depending on the application of the liquid injection molding apparatus10, injector 15 may require frequent cleaning of feed screw 37necessitating the removal of feed screw 37 from feed screw motor 35.FIG. 4 illustrates an embodiment of injector 15 including a bayonetconnector 65 removably coupling a drive shaft 70 of feed screw motor 35to feed screw 37.

Referring to FIG. 4 and FIG. 5, bayonet connector 65 includes a receiver75 and an insert 80 including a first end 85 and a second end 90 distalfrom first end 85, first end 85 is removably coupled to and housed inreceiver 75, second end 90 is coupled to feed screw 37 (see FIG. 10).Drive shaft 70 defines a hollow portion 95 having a non-roundcross-section. Receiver 75 is shaped for a snug fit and housed in hollowportion 95 such that rotating drive shaft 70 about an axis 100 of driveshaft 70 rotates receiver 75 about axis 100. Insert 80 can be threadablyconnected to feed screw 37 but a person of ordinary relevant skills inthe art would appreciate that other means of connection (e.g., welding,insert 80 formed integral with feed screw 37, etc. . . . ) are possible.

Receiver 75 includes an axial opening 110, and a wall 115 having aninterior surface 120 defining a cylindrical space 125 connected to axialopening 110 (see FIG. 5). In the embodiment illustrated by FIG. 4 andFIG. 5, wall 115 includes at least one lug 130, located distal fromaxial opening 110, projecting from interior surface 120 into cylindricalspace 125 (see FIG. 6 and FIG. 7).

Referring to FIG. 8 and FIG. 9, insert 80 includes an exterior surface135 and at least one slot 140 on exterior surface 135 at first end 85.Slot 140 has an axial leg 145 and a circumferential leg 150,circumferential leg 150 forming an acute angle 155 with the axial leg145 at a junction 160. Axial leg 145 includes a third end 165 distalfrom junction 160. Third end 165 includes an axial opening 170 to permitlug 130 to enter slot 140 when third end 165 engages lug 130.Circumferential leg 150 includes a fourth end 175 distal from junction160 such that, with lug 130 in fourth end 175, rotating receiver 75about an axis 176 of receiver 75 in an angular direction A (see FIG. 5)rotates insert 80 (see FIG. 10).

Referring to FIG. 5 and FIG. 10, injector 15 further comprises a collet180. Drive shaft 70 includes an axial opening 105 connected to hollowportion 95. Collet 180 is threadably connected to axial opening 105 ofdrive shaft 70 to inhibit axial displacement of receiver 75 withinhollow portion 95 thereby inhibiting lug 130 from moving away from thefourth end 175 of circumferential leg 150. In the illustratedembodiment, collet 180 includes a tubular body 181 having an externallythreaded end 182 and a flange 183 at an end opposite externally threadend 182 for gripping to connect or disconnect collet 180 to or fromdrive shaft 70. In the illustrated embodiments, collet 180 isdimensioned to permit feed screw 37 and insert 80 to axially passthrough collet 180. However, a person of ordinary relevant skills in theart would appreciate that collet 180 need not allow both feed screw 37and insert 80 to axially pass through collet 180. It is possible todimension collet 180 to only allow either feed screw 37 or insert 80,rather than both, to axially pass through collet 180.

Receiver 75 includes another axial opening 190, distal from axialopening 110 of receiver 75, and connected to cylindrical space 125 (seeFIG. 6). That is, cylindrical space 125 spans both axial openings 110,190. First end 85 of insert 80 extends through receiver 75 passingthrough both axial openings 110, 190 of receiver 75. That is, whencollet 180 urges receiver 75 towards drive shaft 70 seating lug 130 infourth end 175 of circumferential leg 150 (i.e., lug 130 abuts fourthend 175), a gap 195 separates receiver 75 from an axial surface 200 ofdrive shaft 70. Axial surface 200 forms a closed end of hollow portion95. In the illustrated embodiments, insert 80 abuts axial surface 200for transmitting an axial force experienced by feed screw 37 to driveshaft 70 (see FIG. 10). And because receiver 75 does not touch axialsurface 200, when collet 180 seats lugs 130 in fourth end 175 of slots140, receiver 75 is inhibited from any axial displacement within hollowportion 95 thereby inhibiting lugs 130 from separating from slots 140.

Wall 115 includes an exterior surface 205 including four planar sides210 and four chamfers 215, each chamfer 215 connecting twointerconnected planar sides 210

In the illustrated embodiments, exterior surface 135 of insert 80includes two radially spaced apart planar portions 220 to provide asurface for gripping during coupling or decoupling insert 80 fromreceiver 75.

FIG. 11 and FIG. 12 illustrate another embodiment of bayonet connector65 generally indicated by 65 a. Bayonet connector 65 a includes slots140 a in the receiver 75 a and lugs 130 a on insert 80 a rather than thearrangement illustrated by FIG. 5 with slots 140 on insert 80 and lugs130 in receiver 75. Features common to both embodiments bear the samereference characters. Features of the embodiment illustrated in FIG. 11and FIG. 12 that are variants of their counterparts of the embodiment ofFIG. 5 bear the same reference character as their counterpart exceptwith letter “a” appended to the reference character. Receiver 75 aincludes an axial opening 110 a, and a wall 115 a including an interiorsurface 120 a defining a cylindrical space 125 a connected to axialopening 110 a. Insert 80 a includes an exterior surface 135 a havinglugs 130 a, at first end 85 a, projecting radially away from exteriorsurface 135 a. Interior surface 120 a includes slots 140 a having anaxial leg 145 a and a circumferential leg 150 a. Circumferential leg 150a forming an acute angle 155 a with axial leg 145 a at a junction 160 a.Axial leg 145 a includes a third end 165 a distal from junction 160 a.Third end 165 a includes an axial opening 170 a to permit lug 130 a toenter slot 140 a when third end 165 a engages lug 130 a. Circumferentialleg 150 a includes a fourth end 175 a distal from junction 160 a suchthat, with lug 130 a in fourth end 175 a, rotating receiver 75 a aboutaxis 176 a of receiver 75 a in an angular direction B (see FIG. 11)rotates insert 80 a.

In the embodiment illustrated in FIG. 11, receiver 75 a includes anexterior surface 205 including four planar sides 210 and four chamfers215, each chamfer 215 connecting two interconnected planar sides 210 ofthe four planar sides 210. In some embodiments (e.g., FIG. 5 and FIG.11), four lugs 130, 130 a and four corresponding slots 140, 140 a areused with a lug 130, 130 a located at a respective chamfer 215. In someembodiments, lugs 130 are located at a respective chamfer 215.

In the embodiment illustrated in FIG. 12, slots 130 a extend frominterior surface 120 a completely to exterior surface 205 a. In theembodiment illustrated in FIG. 11, slots 130 a extend only partiallyinto wall 115 a from interior surface 120 a.

In some embodiments, hollow portion 95 has a square cross-section (see,for example, FIG. 5). In some embodiments, hollow portion 95 has arounded rectangular cross-section (see, for example, FIG. 13). However,a person of ordinary relevant skills in the art would appreciate thathollow portion 95 can have other cross-sections such as a hexagon, anoctagon, or a D-shape.

In some embodiments, two lugs 130, 130 a and two corresponding slots140, 140 a are used (see, for example, FIG. 13).

In prior art apparatuses, the feed screw is threadably connected to thedrive shaft of the feed screw motor. Consequently, connecting the feedscrew to the drive shaft of the feed screw motor requires rotating thefeed screw relative to the drive shaft of the feed screw motor until thedesire torque is reached. Many revolutions of the feed screw arerequired to connect feed screw to or disconnect the feed screw from thedrive shaft of the feed screw motor. Rotating the feed screw relative tothe drive shaft of the feed screw motor can be cumbersome especially ifit is desirable to be able to detach the feed screw from the drive shaftwhile the feed screw remains within the barrel. With the features taughtby the present application, feed screw 37 will only need to be rotatedby a fraction of a revolution to connect feed screw 37 to or disconnectfeed screw 37 from drive shaft 70. Connecting feed screw 37 to driveshaft 70 can be effected by inserting receiver 75, 75 a into hollowportion 95; inserting insert 80, 80 a (connected to feed screw 37) intoreceiver 75, 75 a by engaging lugs 130, 130 a with respective slots 140,140 a; rotating insert 80, 80 a in the angular direction to seat lugs130, 130 a in fourth ends 175, 175 a; and tightening collet 180 to driveshaft 70 to prevent axial displacement of receiver 75, 75 a relative tohollow portion 95.

While various embodiments according to the present application have beendescribed above, it should be understood that they have been presentedby way of illustration and example only, and not limitation. It will beapparent to persons of ordinary relevant skill in the relevant art thatvarious changes in form and detail can be made therein without departingfrom the scope of the invention. It will also be understood that eachfeature of each embodiment discussed herein, may be used in combinationwith the features of any other embodiment. Thus, the breadth and scopeof the present invention should not be limited by the above-describedexemplary embodiments, but should be defined only in accordance with theappended claims and their equivalents.

1.-16. (canceled)
 17. A liquid injection molding apparatus comprising: amold assembly; a clamping unit; and an injector including a barrel, afeed screw concentrically located in the barrel, and a motor having adrive shaft removably coupled to the feed screw via a bayonet connector,the drive shaft including a hollow portion having a non-roundcross-section.
 18. The liquid injection molding apparatus of claim 17,wherein the bayonet connector includes a receiver shaped for a snug fitand housed in the hollow portion of the drive shaft such that rotatingthe drive shaft about an axis of the drive shaft rotates the receiver,and an insert including a first end removably coupled to and housed inthe receiver, and a second end distal from the first end and coupled tothe feed screw.
 19. The liquid injection molding apparatus of claim 18,wherein the receiver of the bayonet connector includes an axial opening,and a wall including an interior surface defining a cylindrical spaceconnected to the axial opening, the wall including at least one lugprojecting from the interior surface into the cylindrical space, distalfrom the axial opening, and the insert of the bayonet connector includesan exterior surface, and at least one slot on the exterior surface atthe first end, the at least one slot having an axial leg and acircumferential leg, the circumferential leg forming an acute angle withthe axial leg at a junction, the axial leg including a third end distalfrom the junction, the third end including an axial opening to permitthe at least one lug to enter the at least one slot when the third endengages the at least one lug, the circumferential leg including a fourthend distal from the junction such that rotating the receiver about anaxis of the receiver in an angular direction to seat the at least onelug in the fourth end rotates the insert.
 20. The liquid injectionmolding apparatus according to claim 19, further comprising a collet,the drive shaft including an axial opening connected to the hollowportion, the collet threadably connected to the axial opening of thedrive shaft to inhibit axial displacement of the receiver within thehollow portion thereby inhibiting the at least one lug from moving awayfrom the fourth end.
 21. The liquid injection molding apparatus of claim20, wherein the receiver of the bayonet connector includes another axialopening, distal from the axial opening of the receiver, connected to thecylindrical space, the first end of the insert extends through thereceiver passing through both axial openings of the receiver.
 22. Theliquid injection molding apparatus of claim 21, wherein the at least onelug includes more than one lug and the at least one slot includes morethan one slot, each slot engaging a respective one of the more than onelug.
 23. The liquid injection molding apparatus of claim 22, wherein theinsert of the bayonet connector is threadably connected to the feedscrew.
 24. The liquid injection molding apparatus of claim 19, whereinthe wall includes an exterior surface including four planar sides andfour chamfers, each chamfer connecting two interconnected planar sidesof the four planar sides, the at least one lug includes four lugs andthe at least one slot includes four slots, each lug located at arespective chamfer.
 25. The liquid injection molding apparatus of claim18, wherein the insert of the bayonet connector includes an exteriorsurface having at least one lug, at the first end, projecting radiallyaway from the exterior surface, and the receiver of the bayonetconnector includes an axial opening, and a wall including an interiorsurface defining a cylindrical space connected to the axial opening, theinterior surface including at least one slot having an axial leg and acircumferential leg, the circumferential leg forming an acute angle withthe axial leg at a junction, the axial leg including a third end distalfrom the junction, the third end including an axial opening to permitthe at least one lug to enter the at least one slot when the third endengages the at least one lug, the circumferential leg including a fourthend distal from the junction such that rotating the receiver about anaxis of the receiver in an angular direction to seat the at least onelug in the fourth end rotates the insert.
 26. The liquid injectionmolding apparatus according to claim 25, further comprising a collet,the drive shaft including an axial opening connected to the hollowportion, the collet threadably connected to the axial opening of thedrive shaft to inhibit axial displacement of the receiver within thehollow portion thereby inhibiting the at least one lug from moving awayfrom the fourth end.
 27. The liquid injection molding apparatus of claim26, wherein the receiver of the bayonet connector includes another axialopening, distal from the axial opening of the receiver, connected to thecylindrical space, the first end of the insert extends through thereceiver passing through both axial openings of the receiver.
 28. Theliquid injection molding apparatus of claim 27, wherein the at least onelug includes more than one lug and the at least one slot includes morethan one slot, each slot engaging a respective one of the more than onelug.
 29. The liquid injection molding apparatus of claim 28, wherein theinsert of the bayonet connector is threadably connected to the feedscrew.
 30. The liquid injection molding apparatus of claim 25, whereinthe receiver of the bayonet connector includes an exterior surfaceincluding four planar sides and four chamfers, each chamfer connectingtwo interconnected planar sides of the four planar sides, the at leastone lug includes four lugs and the at least one slot includes fourslots, each axial leg located at a respective chamfer.
 31. The liquidinjection molding apparatus of claim 30, wherein the at least one slotextends from the interior surface to the exterior surface of thereceiver.
 32. The liquid injection molding apparatus according to claim17, wherein the non-round cross-section of the hollow portion of thedrive shaft is a rounded rectangular cross-section.
 33. The liquidinjection molding apparatus according to claim 17, wherein the non-roundcross-section of the hollow portion of the drive shaft is a hexagonalcross-section.
 34. The liquid injection molding apparatus according toclaim 17, wherein the non-round cross-section of the hollow portion ofthe drive shaft is an octagonal cross-section.
 35. The liquid injectionmolding apparatus according to claim 17, wherein the non-roundcross-section of the hollow portion of the drive shaft is a D-shapedcross-section.
 36. The liquid injection molding apparatus according toclaim 17, wherein the non-round cross-section of the hollow portion ofthe drive shaft is a square cross-section.